A mashing method as described above is disclosed in British patent GB-B 879 470. More specifically, said British patent describes a continuous method for the production of brewer's wort wherein heat-treated mash is introduced onto a first screen separator. The spent grains passing off the first screen separator drop into a first wash vessel where they are met and mixed with a very dilute wort originating from the screen separation of a grain slurry of a second wash vessel. The mixed slurry in the first wash vessel overflows onto a second screen separator. The dilute wort passing through the second screen separator is recirculated to the mashing step and the spent grains passing off the screen drop into the second wash-vessel where it is combined with a water stream. The slurry in second wash vessel overflows onto a third screen separator. The very dilute wort passing through the screen is pumped to the first wash vessel and the spent grains discharged from the screen go to spent grain disposal.
The method described in the British patent comprises continuously subjecting the solids fraction to counter-current extraction in a plurality of stages, each of which stages comprises reslurrying with wash effluent from a succeeding stage and mechanical separation of the coarse solids, to produce a substantially fully exhausted coarse solids waste. The examples of the British patent describe the results of three different production runs. The process wort streams produced in these runs had a specific gravity (S.G.) in the range of 1.04117 to 1.04484. These specific gravities equate to a gravity of about 10-11 degrees Plato (° P).
DE-B 516 547 describes an apparatus in which mash is separated into fermentable mash extract and wet spent grain by passing mash across a grid, followed by pressing the wet spent grains so obtained by means of a press piston against a sieve to obtain dewatered spent grain and additional fermentable mash extract.
DE-B 165 124 describes a process for continuous wort production that employs a sequence of three press chambers. The first and third chamber contain a screw press that is mounted in a conically shaped cylinder. This cylinder is perforated or comprises a mesh screen in order to allow liquid to run off. The second chamber is used for sparging the spent grain that exits from the first chamber before it is transferred into the third chamber. Sparging water is utilized in the process in a countercurrent fashion. In the process disclosed in the German patent sieving and pressing occur essentially simultaneous.
U.S. Pat. No. 3,157,583 describes a process for the production of clarified malt extract wherein mash is passed through a first vibrating screen to remove most of the fibrous and husk material and wherein the removed fibrous and husk material is transferred to another vibrating screen where it is washed with sparging water.